1. Field of the Invention
The present invention relates to a matrix display device and a method of driving the same, and more particularly, the present invention is preferably applied to a video signal line drive circuit, a scanning line drive circuit, and a timing controller for controlling these circuits, which are incorporated in the matrix display device.
2. Description of the Background Art
Conventionally, there has been a well-known technique relating to timing controllers incorporated in liquid crystal displays, which could be used for liquid crystal panels of various resolutions (Japanese Patent Application Laid Open Gazette No. 2009-265132: Patent Document 1). When such a timing controller generates control signals thereinside in order to control video signal line drive circuits and scanning line drive circuits, the timing controller needs to hold the respective resolutions in vertical and horizontal directions of the liquid crystal panel as parameters. Further, by using the parameters, the timing controller needs to have a counter circuit which is provided thereinside count up to near at least the resolutions.
By using the count value of the counter, it is possible to measure the timing of generating the control signals for controlling the video signal line drive circuits and the scanning line drive circuits and generate various control signals as appropriate.
The signals needed to control the horizontal direction (the video signal line drive circuits) mainly include an image display data signal (representing digital image signals for red, green, and blue, each of which is a bus with several bit width), a horizontal start pulse used by the video signal line drive circuits to determine the start of capture of a valid image display data signal together with a horizontal clock serving as a reference for these operations, a polarity switching signal indicating a polarity in driving the liquid crystal, a latch pulse for transmitting the image display data signal to an output side of the video signal line drive circuit, and the like. Hereinafter, a region in which one red pixel image, one green pixel image, or one blue pixel image is displayed is referred to as one pixel.
In the technique disclosed in Japanese Patent Application Laid Open Gazette No. 2009-265132 (Patent Document 1), a pulse outputted from the output side of a video signal line drive circuit in the last stage of scanning in the horizontal direction is reused in the video signal line drive circuit or the timing controller, to thereby generate a latch pulse. Because of this characteristic feature, it is not necessary to hold the resolution in the horizontal direction as a parameter in the timing controller and therefore, no register or memory for holding the resolution in the timing controller needs to be provided. Further, no external memory of the timing controller for holding the resolution needs to be provided.
Only by the above technique, however, the vertical scan cannot be handled. In the vertical scan, especially, the respective writing times for all the scanning lines basically need to be the same, conventionally, and for this reason, a vertical clock used for the vertical scan needs to be repeated in the same cycle at the same duty ratio, (the number of scanning lines+1) times or more. Therefore, a register or a memory for holding a parameter by which the timing controller knows the number of scanning lines, and a counter circuit are needed.